A few short tips:
a) learn to slide in to the ball. Not so easy to do in short time.
b) topspin will bounce high, but a slice will skid off the surface with a lower bounce. Pick your shots.
c) Hit behind your opponent. Clay is slippery and it's hard to change direction. Be ready for your opponent doing this to you.
d) drop shots are particularly effective on clay.
e) flat serves are not that effective unless you have a real killer. Better to slice or kick the serve.
I've never played on green clay but if it's anything like red clay the tips above will be useful.